Applicant claims priority under 35 U.S.C. xc2xa7119 of German Application No. 100 29 725.0, filed on Jun. 16, 2000. Applicant also claims priority under 35 U.S.C. xc2xa7120 of PCT/DE01/02128, filed on Jun. 7, 2001. The international application under PCT article 21(2) was not published in English.
The invention relates to a method for marking defects detected in/on rod-shaped rolled material.
As a rule, steel products that have already been rolled to the finished quality are checked for internal and external defects with the help of suitable test devices.
For the detection of internal defects, ultrasound test heads are employed, among other devices, and for the detection of surface defects, for example production line coils or eddy-current probes rotating around the rolled material are used.
The determined defects are marked on the product, for example on a round rod, either over the entire circumference or only locally depending on the type of flaw detected. Surface defects do not always lead to sorting out of the rods because it may be possible to repair the flawed rods. Internal defects cannot be repaired. The defective piece has to be cut out.
As a rule, internal defects are caused already in the course of the casting process, or originate in the cooled-down steel block from which the rods are to be rolled.
The greater the length to which such a steel block is rolled out, in the end effect up to the rod-shaped final product, the more difficult it is to detect the internal defects. It therefore happens that defects present in the starting product can no longer be detected in the finished product.
Therefore, in connection with the method described, the testing for defects and the marking of the defects start only after the material processed for an order has been rolled out. This means that each rod has to be checked (after the rod material has been cut to the length specified by the customer, as a rule) in a separate work operation.